LinkedIn is locked in to a successful if lackluster business model, as far as Wall Street—and the online social network's 40 to 43 million reguar unique visitors—are concerned. That puts it in contrast to many of the sexier brands in the social media-sphere.

While the market capitalizations of darlings such as Facebook, Zynga and Groupon have fallen by 25 percent to 60 percent since their recent public offerings, LinkedIn is now valued at more than $18 billion versus just $4 billion when it went public nearly two years ago. With that, its stock closed at all-time highs this week.

That's because the Mountain View, Calif.-based brand has managed to create and then dominate social media networking focused around jobs, careers and business identities. LinkedIn also has been able to monetize its site by selling services such as job ads, career pages and a recruiter talent finder that helps companies find, attract and manage their talent.

In turn, LinkedIn's utility has helped make it gradually more attractive to the most career-challenged generation—Milennials—in addition to Generation Xers and boomers who tended to become the initial members of LinkedIn as established professionals. Meanwhile, Facebook, for instance, has lost its identity as the place where young social-networkers gather.

"Originally," LinkedIn "was seen as your mom's or your dad's network," Phil Hendrickson, manager of global talent and sourcing strategy for Starbucks, told the Wall Street Journal. "Now it also has more young professionals and college-level folks."

LinkedIn continues to boost its usefulness as well. It is pushing into content by aggregating business news, hosting expert blog posts and latching onto continuing personalities such as Virgin Group's Richard Branson, all geared toward keeping users on its site.

By trying not to be all things to all people online, but by insinuating itself as an omnibus platform for a narrower group, LinkedIn seems to be succeeding where alternate business models have failed.

LinkedIn isn't the only company benefiting from the social platform. Recently, HP was the first company with a LinkedIn page to break 1 million followers. The milestone means that HP's page is connected to over 43 million people, all who will see HP's content and job postings.

"LinkedIn has been critical for HP in successfully reaching and building relationships with our community of customers, partners and prospective employees," said Natalie Malaszenko, vice president of digital marketing at HP.

According to a study by the University of Massachusetts at Dartmouth, LinkedIn has officially grabbed the corporate social media reigns from Facebook. Results showed that 81 percent of Inc. 500 businesses use LinkedIn, while only 67 percent use Facebook.